I'm not sure whether it is problem of cache, hibernate or my design. Please
give me an advise if there's a well-known pattern to solve this.
Suppose I have an entity with two props - key and value mapped to a table with
two fields.
| <hibernate-mapping>
| <class name="test.TestEntity" table="TEST_ENTITY">
| <cache usage="transactional"/>
|
| <id name="id" type="int" >
| <generator class="assigned"/>
| </id>
|
| <property name="value" type="int"/>
| </class>
| </hibernate-mapping>
|
|
Suppose I have a servlet which prints values for keys passed as parameter.
(like /servletName?keyList=1,2,3,4)
Servlet looks like
| void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
|
| StringTokenizer st = new
StringTokenizer(request.getParameter("keyList"), ",");
| UserTransaction utx;
| try {
| utx = (UserTransaction)new
InitialContext().lookup("UserTransaction");
| utx.begin();
|
| Session session =
HibernateContext.getSession("java:/hibernate/SessionFactory");
|
| while(st.hasMoreTokens()){
| Integer id = new Integer(st.nextToken());
|
| System.out.println(""+Thread.currentThread()+" loading
"+id);
| session.load(TestEntity.class, id);
| Thread.sleep(1000);
| }
|
| utx.commit();
| } catch (Exception e) {
| e.printStackTrace();
| }
|
|
|
| }
|
|
If I request simultaneously following url's:
..../servletName?keyList=1,2,3,4,5,6,7,8,9,10
and
..../servletName?keyList=10,9,8,7,6,5,4,3,2,1
I hava 100% chance to get a deadlock.
anonymous wrote :
| 20:06:29,588 INFO [STDOUT] Thread[http-0.0.0.0-8180-Processor25,5,jboss]
loading 1
| 20:06:31,635 INFO [STDOUT] Thread[http-0.0.0.0-8180-Processor24,5,jboss]
loading 10
| 20:06:37,807 INFO [STDOUT] Thread[http-0.0.0.0-8180-Processor25,5,jboss]
loading 2
| 20:06:39,041 INFO [STDOUT] Thread[http-0.0.0.0-8180-Processor25,5,jboss]
loading 3
| 20:06:40,197 INFO [STDOUT] Thread[http-0.0.0.0-8180-Processor25,5,jboss]
loading 4
| 20:06:41,619 INFO [STDOUT] Thread[http-0.0.0.0-8180-Processor25,5,jboss]
loading 5
| 20:06:42,760 INFO [STDOUT] Thread[http-0.0.0.0-8180-Processor25,5,jboss]
loading 6
| 20:06:43,057 INFO [STDOUT] Thread[http-0.0.0.0-8180-Processor24,5,jboss]
loading 9
| 20:06:43,901 INFO [STDOUT] Thread[http-0.0.0.0-8180-Processor25,5,jboss]
loading 7
| 20:06:44,229 INFO [STDOUT] Thread[http-0.0.0.0-8180-Processor24,5,jboss]
loading 8
| 20:06:45,119 INFO [STDOUT] Thread[http-0.0.0.0-8180-Processor25,5,jboss]
loading 8
| 20:06:45,401 INFO [STDOUT] Thread[http-0.0.0.0-8180-Processor24,5,jboss]
loading 7
| 20:07:00,135 ERROR [IdentityLock] read lock for
//hibernate/test/TestEntity/8 could not be acquired after 15000 ms. Lock
| map ownership Read lock owners: []
| Write lock owner: :2
| (caller=:1)
| 20:07:00,166 INFO [STDOUT] net.sf.hibernate.cache.CacheException:
org.jboss.cache.lock.TimeoutException: lock for //hibe
| rnate/test/TestEntity/8 could not be acquired after 15000ms. Lock map
ownership Read lock owners: []
| Write lock owner: :2
|
| at net.sf.hibernate.cache.TreeCache.get(TreeCache.java:61)
| at
net.sf.hibernate.cache.TransactionalCache.get(TransactionalCache.java:29)
| at net.sf.hibernate.impl.SessionImpl.doLoad(SessionImpl.java:2121)
| at
net.sf.hibernate.impl.SessionImpl.doLoadByClass(SessionImpl.java:2000)
| at net.sf.hibernate.impl.SessionImpl.load(SessionImpl.java:1929)
| at test.TestCacheLockServlet.service(TestCacheLockServlet.java:57)
| at javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
| at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:237)
| at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157)
| at
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:75)
| at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:186)
| at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157)
| at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:214)
| at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
| at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
| at
org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:198)
| at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:152)
| at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
| at
org.jboss.web.tomcat.security.CustomPrincipalValve.invoke(CustomPrincipalValve.java:66)
| at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:102)
| at
org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:162)
| at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:102)
| at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
| at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:137)
| at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
| at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:118)
| at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:102)
| at
org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:535)
| at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:102)
| at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
| at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
| at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
| at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
| at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:929)
| at
org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:160)
| at
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:799)
| at
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:705)
| at
org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:577)
| at
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:683)
| at java.lang.Thread.run(Thread.java:595)
| Caused by: org.jboss.cache.lock.TimeoutException: lock for
//hibernate/test/TestEntity/8 could not be acquired after 1500
| 0ms. Lock map ownership Read lock owners: []
| Write lock owner: :2
|
| at
org.jboss.cache.lock.IdentityLock.acquireReadLock(IdentityLock.java:218)
| at org.jboss.cache.Node.acquireReadLock(Node.java:418)
| at org.jboss.cache.Node.acquire(Node.java:399)
| at
org.jboss.cache.interceptors.LockInterceptor.lock(LockInterceptor.java:202)
| at
org.jboss.cache.interceptors.LockInterceptor.invoke(LockInterceptor.java:144)
| at
org.jboss.cache.interceptors.Interceptor.invoke(Interceptor.java:40)
| at
org.jboss.cache.interceptors.CreateIfNotExistsInterceptor.invoke(CreateIfNotExistsInterceptor.java:50)
| at
org.jboss.cache.interceptors.Interceptor.invoke(Interceptor.java:40)
| at
org.jboss.cache.interceptors.UnlockInterceptor.invoke(UnlockInterceptor.java:35)
| at org.jboss.cache.TreeCache.invokeMethod(TreeCache.java:2978)
| at org.jboss.cache.TreeCache.get(TreeCache.java:1509)
| at org.jboss.cache.TreeCache.get(TreeCache.java:1493)
| at net.sf.hibernate.cache.TreeCache.get(TreeCache.java:58)
| ... 39 more
| 20:07:00,401 ERROR [IdentityLock] read lock for
//hibernate/test/TestEntity/7 could not be acquired after 15000 ms. Lock
| map ownership Read lock owners: []
| Write lock owner: :1
| (caller=:2)
| 20:07:00,416 INFO [STDOUT] net.sf.hibernate.cache.CacheException:
org.jboss.cache.lock.TimeoutException: lock for //hibe
| rnate/test/TestEntity/7 could not be acquired after 15000ms. Lock map
ownership Read lock owners: []
| Write lock owner: :1
|
| at net.sf.hibernate.cache.TreeCache.get(TreeCache.java:61)
| at
net.sf.hibernate.cache.TransactionalCache.get(TransactionalCache.java:29)
| at net.sf.hibernate.impl.SessionImpl.doLoad(SessionImpl.java:2121)
| at
net.sf.hibernate.impl.SessionImpl.doLoadByClass(SessionImpl.java:2000)
| at net.sf.hibernate.impl.SessionImpl.load(SessionImpl.java:1929)
| at test.TestCacheLockServlet.service(TestCacheLockServlet.java:57)
| at javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
| at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:237)
| at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157)
| at
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:75)
| at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:186)
| at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157)
| at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:214)
| at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
| at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
| at
org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:198)
| at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:152)
| at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
| at
org.jboss.web.tomcat.security.CustomPrincipalValve.invoke(CustomPrincipalValve.java:66)
| at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:102)
| at
org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:162)
| at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:102)
| at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
| at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:137)
| at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
| at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:118)
| at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:102)
| at
org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:535)
| at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:102)
| at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
| at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
| at
org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
| at
org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
| at
org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:929)
| at
org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:160)
| at
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:799)
| at
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:705)
| at
org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:577)
| at
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:683)
| at java.lang.Thread.run(Thread.java:595)
| Caused by: org.jboss.cache.lock.TimeoutException: lock for
//hibernate/test/TestEntity/7 could not be acquired after 1500
| 0ms. Lock map ownership Read lock owners: []
| Write lock owner: :1
|
| at
org.jboss.cache.lock.IdentityLock.acquireReadLock(IdentityLock.java:218)
| at org.jboss.cache.Node.acquireReadLock(Node.java:418)
| at org.jboss.cache.Node.acquire(Node.java:399)
| at
org.jboss.cache.interceptors.LockInterceptor.lock(LockInterceptor.java:202)
| at
org.jboss.cache.interceptors.LockInterceptor.invoke(LockInterceptor.java:144)
| at
org.jboss.cache.interceptors.Interceptor.invoke(Interceptor.java:40)
| at
org.jboss.cache.interceptors.CreateIfNotExistsInterceptor.invoke(CreateIfNotExistsInterceptor.java:50)
| at
org.jboss.cache.interceptors.Interceptor.invoke(Interceptor.java:40)
| at
org.jboss.cache.interceptors.UnlockInterceptor.invoke(UnlockInterceptor.java:35)
| at org.jboss.cache.TreeCache.invokeMethod(TreeCache.java:2978)
| at org.jboss.cache.TreeCache.get(TreeCache.java:1509)
| at org.jboss.cache.TreeCache.get(TreeCache.java:1493)
| at net.sf.hibernate.cache.TreeCache.get(TreeCache.java:58)
| ... 39 more
|
|
The thing is: when I try to read an entity which is missing in cache it is
loaded from storage and get written to cache leaving a write lock.
As soon as entities get evicted from cache, ANY "read" of entity can become
"write" to cache requiring write lock.
My question is: is it possible to avoid deadlocks when reading entities in
random order (very common scenario).
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